1. Field of the Invention
The present invention is directed to a blur correcting apparatus used for cameras which prevents an image on a film plane from blurring due to a displacement of an optical axis of a photographing optical system of a camera, caused, for example, by camera shakes.
2. Description of Related Art
When a picture is taken by a camera, particularly, when the camera is hand held without using a tripod, an accidental movement of the optical axis of the photographing optical system of the camera tends to occur due to camera shakes. These are caused particularly when the camera is not held stably by the photographer, a picture of a dark object is taken at a slow shutter speed, or the photographer takes a picture while moving, etc. The blurred picture is not clearly seen due to a streaked image. The blur caused by the camera shake can be eliminated to some extent, using a hardware solution of a bright lens or increasing the film sensitivity to increase the shutter speed, or by a software solution of improving the photographer's skill.
A blur correcting apparatus which can prevent the occurrence of blurring due to camera shake has been proposed, in which an angular velocity or the acceleration of the camera is detected and the blur correcting lens is moved in an opposite direction to the direction of the camera shake to prevent a movement of the image on the film plane.
When a blur correcting apparatus of this type is adopted for a still camera, the occurrence of blurring can be prevented only if the apparatus functions during the exposure of the camera. However, in the case of an SLR camera, if the apparatus functions only during the exposure, a photographer cannot tell, through the use of the viewfinder of the camera, whether the apparatus is properly functioning since the photographer cannot see through the view finder during the exposure due to a blackout of the finder view, which is peculiar to SLR cameras. For this reason, in photography using a SLR camera, some photographers cannot rely on the blur correcting apparatus since they cannot visually make sure if the apparatus is in operation while taking a picture.